From b33d967548ec795a3ba5ac29f7a697555b595ab2 Mon Sep 17 00:00:00 2001
From: Xiang Xiao <xiaoxiang@xiaomi.com>
Date: Wed, 20 Jan 2021 21:31:09 +0800
Subject: [PATCH] fs/tmpfs: Iterate the entry reversely in readdir

to avoid readdir return the wrong entry in the following code:
void rmdir_recursive(FAR const char *path)
{
  FAR DIR *dir = opendir(path);

  while (1)
    {
      char fullpath[MAX_PATH];
      FAR dirent *ent = readdir(dir);

      if (ent == NULL)
        {
          break;
        }

      sprintf(fullpath, "%s/%s", path, ent->d_name);
      if (DIRENT_ISDIRECTORY(ent->d_type))
        {
          rmdir_recursive(fullpath);
        }
      else
        {
          unlink(fullpath);
        }
    }
}

Signed-off-by: Xiang Xiao <xiaoxiang@xiaomi.com>
Change-Id: Ide60fe8db6aada88ad3d8e45367f11599a6f33b1
---
 fs/tmpfs/fs_tmpfs.c | 19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

diff --git a/fs/tmpfs/fs_tmpfs.c b/fs/tmpfs/fs_tmpfs.c
index 85682620320..c9cf528b7d7 100644
--- a/fs/tmpfs/fs_tmpfs.c
+++ b/fs/tmpfs/fs_tmpfs.c
@@ -1962,7 +1962,7 @@ static int tmpfs_opendir(FAR struct inode *mountpt, FAR const char *relpath,
   if (ret >= 0)
     {
       dir->u.tmpfs.tf_tdo   = tdo;
-      dir->u.tmpfs.tf_index = 0;
+      dir->u.tmpfs.tf_index = tdo->tdo_nentries;
 
       tmpfs_unlock_directory(tdo);
     }
@@ -2022,7 +2022,7 @@ static int tmpfs_readdir(FAR struct inode *mountpt,
   /* Have we reached the end of the directory? */
 
   index = dir->u.tmpfs.tf_index;
-  if (index >= tdo->tdo_nentries)
+  if (index-- == 0)
     {
       /* We signal the end of the directory by returning the special error:
        * -ENOENT
@@ -2059,9 +2059,9 @@ static int tmpfs_readdir(FAR struct inode *mountpt,
 
       strncpy(dir->fd_dir.d_name, tde->tde_name, NAME_MAX + 1);
 
-      /* Increment the index for next time */
+      /* Save the index for next time */
 
-      dir->u.tmpfs.tf_index = index + 1;
+      dir->u.tmpfs.tf_index = index;
       ret = OK;
     }
 
@@ -2076,12 +2076,19 @@ static int tmpfs_readdir(FAR struct inode *mountpt,
 static int tmpfs_rewinddir(FAR struct inode *mountpt,
                            FAR struct fs_dirent_s *dir)
 {
+  FAR struct tmpfs_directory_s *tdo;
+
   finfo("mountpt: %p dir: %p\n",  mountpt, dir);
   DEBUGASSERT(mountpt != NULL && dir != NULL);
 
-  /* Set the readdir index to zero */
+  /* Get the directory structure from the dir argument and lock it */
 
-  dir->u.tmpfs.tf_index = 0;
+  tdo = dir->u.tmpfs.tf_tdo;
+  DEBUGASSERT(tdo != NULL);
+
+  /* Set the readdir index pass the end */
+
+  dir->u.tmpfs.tf_index = tdo->tdo_nentries;
   return OK;
 }